Deciphering Caenorhabditis elegans molecular nociception using mass spectrometry-based proteomics and network biology

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Caenorhabditis elegans (C.elegans) is a powerful animal model system for functional genomics relevant to mammalian biology and it is extensively used to study nociceptive behavior. Interestingly, adult C.elegans consists of 959 cells, of which 302 are neurons, which make this model attractive to study nociception at the physiological and molecular levels. Transient receptor potential (TRP) channels have a central role in the processing of nociceptive chemical and thermal stimuli. In mammals, the activation of TRP channels triggers the propagation of sensory information back to the central nervous system, which leads to pain sensation. Pro-inflammatory sensory neuropeptides, such as tachykinins are released from these activated nerve endings resulting in neurogenic inflammation. At the spinal level, neuropeptides play a central role in pain transmission and in the synaptic chemistry. The C.elegans genome encodes several TRP channels covering all of the seven TRP subfamilies including TRPV analogs (e.g. OSM-9 and OCR1-4). It has been recently established that C.elegans TRP channels are associated with behavioral and physiological processes, including sensory transduction. Many C.elegans TRP channels share similar activation and regulatory mechanisms with their vertebrate counterparts. Moreover, recent studies revealed that neuropeptides from the MSFamide family (NLPs) and FMRamide-related peptides (FLPs) share functional similarities with mammal neuropeptides but very few have been thoroughly characterized. Neuropeptides are involved in the modulation of essentially all behaviors including locomotion, mechano- and chemosensation. Neuropeptides are acting as neuromodulators and as fast neurotransmitters. The broad existence of these neuropeptides in nematodes suggests a fundamental role of neuropeptidergic signalling in C.elegans but the mechanistic knowledge remains very limited. The objectives of the proposed research will be to (1) Quantify nociceptive behaviors of wild type and targeted mutant (e.g. OSM-9, OCR1-4) C.elegans associated with thermal and chemical stimuli; (2) Characterize C.elegans by mass spectrometry using proteomic bottom-up approaches and SILAC normalization; (3) Generate comprehensive bioinformatics analyses (e.g. Ingenuity Pathway Analysis, GeneMANIA) using the proteomic data to identify relationships, mechanisms, functions, biological networks and pathways of relevance. We believed it will provide significant insight in the molecular events implicated in C.elegans nociceptive behaviors and chemical synapses. A better comprehension of these mechanisms in C.elegans will transform our powers of investigation, allowing us, and others, to pursue more comprehensive study of nociception at the molecular level.**